efi gurus : tbi or multi port injection

have stroked 350 its now 388 cid was going to put modified tbi unit from turbo city but now thinking a edelbrock multiport job any suggestions? want to wring most power out of it i can not sure if tbi will give me the best performance 88 blazer /forums/images/graemlins/k5.gif

Multi-port is the way to go. better MPG, more power etc. if u can, i'd go with a TPI unit off of a camaro or firebird. IMHO, one of the better units FI wise ever made. ive always been impressed with the power they had. the TBI is just basically an economical carb, but the MPFI systems put a more dense fog right into the intake of the cylinder causing better combustion and more power. /forums/images/graemlins/thumb.gif

I haven't looked into much yet, but I have a 383 project in mind and was thinking of a stand alone MPFI from edlebrock if they have a new chip setup for the 383. I was going to start researching after the 1st of the year, keep us posted on what you do /forums/images/graemlins/thumb.gif

If you have the funds the aftermarket MPFI is the way to go. I am installing stock TPI right now because everyone told me that it is awesome and the price was right. I have heard that the Edelbrock and Holley MPFI systems are easier to install and are probably more reliable due to the fact that all the parts are brand new and not part of a 10+ year old system.

If you want performance MPFI is the only option. TBI can be made to work but MPFI will make more power.

PM Derf00, he has the Edelbrock set up on his 383.........I think all things equal (money being no object /forums/images/graemlins/smirk.gif) I'd go that route in a heartbeat - even tho I'm a big believer in TPI (had it on my 406 motor in my K5), the aftermarket stuff is easier to fine tune to your motor. TPI is great but the only real way to get all you want out of the motor is to get into chip burning and fine tune the heck out of it.......and that takes time, patience and experimentation. /forums/images/graemlins/laugh.gif

MPFI all the way man...TBI is much better tahn a carb in terms of drivability but it still has its limitations. With MPFI, all the cylinders get the same amount of fuel. In a crab or TBI application, cylinders 1 and 2 and 7 and 8 almost ALWAYS run leaners than cylinders 3,4,5,and 6 this is just b/c the fuel has to be distributed to the cylinders via the intake mannie instead of being injected AT the cylinder. This also means that since the intake only has to flow air and isn't required to keep fuel atomized any longer, the intake can have a MUCH smoother surface and yield higher flow numbers. I will take my TBI on my big block ANY day but will be ditching the TBI in the near future for a custom MPFI setup.

Basically, over TBI, MPFI yields:

-Better fuel distribiton --&gt; smoother idle and more power
-More precise fuel control--&gt; more economy and more power
-TBI inherently can't handle a very long duration cam while MPFI can allowing for a more purpose-oriented engine...Granted if it is in a truck for wheeling, you don't need a 286* @ .050" cam, though it would be fun for playing with ricers /forums/images/graemlins/grin.gif

The ONLY downside of MPFI is that is WILL cost more than TBI.

I honestly feel the best deal in aftermarket MPFI systems is the Edelbrock ProFlo MPFI. Dr. Watson runs it on his green "thing" and from what I hear, likes it.

There is a guy named Jeff Davidson (I know him from the Monte Carlo list, believe his car is an LS) running an Edelbrock EFI setup of some kind with his 385. He's in the mid 12's, and has been running the EFI for quite some time, so if you can open his web page (the link I have isn't working for me, www.jeffd.50megs.com ) you might be able to figure out what setup he's got, and find some info on it.

Im gettin ready to start the final assembly phase of my mpfi 496 (if i ever get enough $$$$ for fuel fittings and lines) I have the edelbrock MPFI/TBI conversion going on it. JetChip can burn you a custom chip for pretty much anything. Edelbrock supplied me a chip, so i sent it to Jet, because the edelbrock chip was for a 112 lobe sep and mines 110. Anyway, they pulled injector codes off it, burned me one, then ripped me a new one for 400...argh. This thing better flyyyyyy lol.

really hmmm, your the first one to down talk the RamJet, I apreitate your comments. So would you think in a closed loop setup the RamJet is now an Automotove application?
and yes the RJ350 is about 4700 smakers complete crate &amp; computer w/harness
Sorry for the post hijack

If the Ramjet is, say, $2000 or less in it's "open loop" configuration, then it's probably "worth it". Like I said, last I had heard, it was a lot of money. Maybe I'm thinking of the 502 Ramjet, but $5000 comes to mind.(note to self: read previous comments in full before responding)

You can buy a used injection setup complete for $500, and put another $500 or so into it for parts. Engine rebuild for $800-1200. Looking at just about $2000 for a closed loop FACTORY system, not something that was an afterthought like the Ramjet's closed loop system.

Don't know what the Edelbrock system runs, but if the Ramjet is anything more than $2000, I think the Edelbrock system has to be better as well.

Ok I cheated. " Your Price - $4,661.30 "

"This new controller fits in the palm of your hand and was originally developed by GM Powertrain for marine applications.
MEFI 3 is ideally suited for use in street rods, street machines and sportsman racers. "

In other words, it was never intended to be used on cars, that is also why it is not emissions legal. Emissions legal doesn't mean it won't smog well, but it's a good indication that it is probably NOT an efficient motor, at least compared to what any other "closed loop" setup designed from the ground up would be.

Now the base/plenum look like a good design for a lot of top end power, (IE boats at high RPM all the time) but IIRC, even the ramjet specific parts alone are more expensive than going with power-oriented aftermarket port injection setups, such as the mini-ram, etc.

WITH This:
Performer Pro-Flo® EFI System
350+ HP Potential from Idle to 5500 rpm
in Small-Block Chevys
The Performer Pro-Flo EFI System for carbureted non-emission engines for more power and driveability in Performer-level engines. Like all Edelbrock EFI Systems, Performer EFI #3503 uses a speed/density system for control over fuel and spark and is ideal for small-block Chevys with up to 9.5:1 compression with mild cams such as the Edelbrock Performer #2102. With an operating range of off-idle to 5500 rpm, this system can be used in any type of vehicle from a 4x4 to a street rod.

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